Genesis 18:9-14 Gen. 18:9-14
9 And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent. 10 And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him. 11 Now Abraham and Sarah were old and well stricken in age; and it ceased to be with Sarah after the manner of women. 12 Therefore Sarah laughed within herself, saying, After I am waxed old shall I have pleasure, my lord being old also? 13 And the LORD said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, which am old? 14 Is any thing too hard for the LORD? At the time appointed I will return unto thee, according to the time of life, and Sarah shall have a son.
Genesis 21:1-5 Gen. 21:1-5
1 And the LORD visited Sarah as he had said, and the LORD did unto Sarah as he had spoken. 2 For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him. 3 And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac. 4 And Abraham circumcised his son Isaac being eight days old, as God had commanded him. 5 And Abraham was an hundred years old, when his son Isaac was born unto him.
(Relation)